c程序设计语言_习题1-19_编写函数reverse(s)将字符串s中字符顺序颠倒过来。

Write a function

reverse(s)

that reverses the character string

s

. Use it to write a program that reverses its input a line at a time.

#include <stdio.h>

#define MAX_LINE 1024

void discardnewline(char s[])
{
int i;
for(i = 0; s[i] != '\0'; i++)
{
if(s[i] == '\n')
s[i] = '\0';
}
}

int reverse(char s[])
{
char ch;
int i, j;

for(j = 0; s[j] != '\0'; j++)
{
}

--j;

for(i = 0; i < j; i++)
{
ch   = s[i];
s[i] = s[j];
s[j] = ch;
--j;
}

return 0;
}

int getline(char s[], int lim)
{
int c, i;

for(i = 0; i < lim - 1 && (c = getchar()) != EOF && c != '\n'; ++i)
{
s[i] = c;
}

if(c == '\n')
{
s[i++] = c;
}

s[i] = '\0';

return i;

}

int main(void)
{
char line[MAX_LINE];

while(getline(line, sizeof line) > 0)
{
discardnewline(line);
reverse(line);
printf("%s\n", line);
}
return 0;
}